Grain door



June 17, 1958 I E, G. STACK 2,838,807

GRAIN DOOR Filed Jan. 12, 1953 v United States Patent C GRAIN DOOR Emmet G. Stack, Portland, Oreg. Application January 12, 1953, Serial No. 330,684

6 Claims. (Cl. 20-35) This application is a continuation in part of my application for Letters Patent for Grain Doors, filed January 8, 1952, Ser. No. 265,481.

The great strength of the grain door shown and described in the above mentioned application comes from the way the cover sheets are arched, namely, lengthwise of the sheet.

The objective of the present invention is to provide a grain door having a greater weight/ strength ratio than the door set forth in the above mentioned application.

The door of this invention is illustrated in the accompanying drawings in which Fig. 1 is a perspective of a door section; Fig. 2 is a longitudinal section on the line 22 of Fig. 1; Fig. 3 is a cross section on the line 3-3 of Fig. 1; Fig. 4 is a cross section on the line 44 of Fig. 1; Fig. 5 is a perspective of one of the longitudinal spacers; Fig. 6 is an elevation showing the door section retaining means in place; and Fig. 7 shows the ends of the three door sections, comprising a grain door, in place against the box car lining and/or door jamb.

Throughout the drawings and the specification similar numerals refer to similar parts.

The nailed-up lumber door, in use for the past 60 years, is spiked in place against the box car lining with from 6 to -20 (1. spikes per door section. Users have the idea that the spikes are for the purpose of holding the door sections in place while the car is being loaded and While it is in transit. Tests show this type of door to have a load capacity of 622# at 1 /2" deflection, and tests also show that by driving 3-20 d. spikes through each end of a door section the load capacity is increased to l0#. This would indicate that the applicants door section would have to have a load capacity of 1510# in order that the spiking of the door 'sections to the car lining and/or door jambs be eliminated, which is one of the objectives of the applicant.

A door section constructed with sill, header, two spacers, and /s" sanded plywood all in accordance with the door section shown in my co-pending application Ser. No. 265,481, carried 1560# at 1 /2" deflection.

It was estimated that A" unsanded plywood would have a strength approximating the sanded plywood and would weigh less and cost less. Accordingly such door sections were made and tested in actual practice. In practice it was found that the inner cover, or the one next to the grain, fractured in the bottom door section about 6" out from the spacer toward the door section ends. It appeared that this might be remedied by increasing the length of the sill and header, namely, by tapering them toward the door section ends. By using unsanded plywood and 48" long tapered sill and header the load capacity was increased to 3415 but the weight was also increased considerably.

7 It was also found that there was a tendency for the plywood between the sill and header to cup under load. By using plywood and 60" tapered sill and header the load capacity was 2780#. By eliminating the two by the numeral 5.

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spacers and using an intermediate member similar to the tapered sill and header, made 72" long, the load capacity was 285 5 and by using two intermediate members the load capacity was increased to 3450#. This latter door section has a strength/weight ratio of 91.4% and a weight of 37.7# as compared to 70# for the standard nailed-up lumber door.

This last mentioned door has been illustrated in the drawings accompanying this-specification in which it is minutely described.

In making up a preferred form of grain door section S, as shown in Fig. 1, two sheets of plywood 2 x 7 in size are used for the covers 1 and 2 which are glued together for a distance of about 4" at their ends or short sides 3 and 4. The glue areas at said ends are indicated Intermediate the covers 1 and 2 are positioned two or more longitudinal spacers 6, four being shown in Fig. 1. Each of the spacers 6 is divided into three equal portions, namely, a middle portion 7 having parallel sides or surfaces 8 and 9, and end portions 10 having sides or surfaces 11 and 12 which con- Thus the form of these spacers 6 causes the verge. cover sheets 1 and 2 to be oppositely arched lengthwise thereof, thus providing maximum strength at the point of the maximum bending moment. The spacers 6 are made 6' in length thus terminating 2" short of the glue areas 5, hence they do not feather out and become easily broken. Four spacers 6 are shown in Fig. l, with the two intermediate spacers 6A equally spaced between the two outside or marginal spacers 6B. If only three spacers 6 are used the intermediate spacer 6A is positioned on the longitudinal centerline 13 of the door section S. The plywood covers 1 and 2 are not only glued together at their ends but to the spacer surfaces 8, 9, 11, and 12. A 4" wide strip of plywood is shown positioned on the door section lateral centerline 14 into which the teeth of the lifting jack (not shown) may bite when the door sections are being lifted to permit the grain to flow out from under said door section when the car' of grain is to be unloaded. This scufiing member 15 serves to stiffen and protect the thin plywood cover 1.

Cascamite, a cold-setting glue, was used for the test panels or door sections but in a mass production layout phenolic resins set with high frequency current would be more practical since grain doors are exposed to the weather at times.

Fig. 6 shows the ends of the covers 1 and 2 to be straight and parallel and of one thickness throughout their width and hence all the door sections S, which are stacked up as in Fig. 7, to make up a grain door D, may lie tight against the box car lining or door jamb 16 when in use.

In the tests made, 3-8 d. double headed nails were driven into the car lining 16 at both ends of each door section S. Each nail 17 was driven through a tar paper roofing washer 18 which overlapped the door section ends. This construction held the door sections S in place during the loading of the car but also while it was in transit. Since none of the nails were driven through the door sections said door sections were readily raised by an ordinary pinch bar. In our co-pending application (Homer S. Sackett and Emmet G. Stack, Ser. No. 237,376) several means were shown which would serve the purpose of the double headed nails.

It might be pointed out that when a test car was being loaded the pressure against the grain door was greatly increased when the grain adjacent the door was Walked upon. This appeared to be due to the fact that grain acts as a semi fluid and does not flow back when the pressure against it is released.

The deflection of 1 /2" referred to was arbitrarily 3 assumed. However, the built-up lumber door deflected considerably more in practice and much depended upon the number and size of nails driven through its ends.

It appears that a plywood door section which is not nailed to the car lining should be designed for four times the theoretical pressure that is expected to come against it.

The results of tests given herein will serve as a guide for: those who wish to vary the size, kind of material, or shape of'members, to meet desired conditions. Plywood has been specifically mentioned for a purpose. However, Masonite and other hardboards have been used for this panel may be used for other purposes too.

What I claim is new in the art follows:

1. A graindoor section comprising a pair of oppositely disposed rectangular cover sheets of greater length than width having a straight face middle portion, two straight face narrow-end portions in a plane parallel to and spaced from the plane of the middle portion, and an inclined portion between the middle portion and each end portion and spacer means having the cover sheets secured thereto said spacer means extending longitudinally between the cover sheets and having the configuration of the middle and inclined portions of the cover sheets, said cover sheets having their end portions secured together.

2. A grain door section comprising a pair of oppositely disposed rectangular cover sheets of greater length than width having a straight face middle portion, two straight face narrow-end portions in a plane parallel to and spaced from the plane of the middle portion, and an inclined portion between the middle portion and each end portion, and spacer means having the cover sheets glued thereto said spacer means extending longitudinally between the cover sheets and having the configuration of the middle and inclined portions of the cover sheets, said cover sheets having their end portions glued together.

3. A grain door section comprising two rectangular cover sheets of greater length than width having the end portions of their adjacent narrow ends glued to each other to form a flat bearing surface on both sides of both ends of the door section that portion of each sheet between said glued together end portions being arched oppositely to the other sheet and a plurality of like longitudinal spacers positioned between and glued to the cover sheets said spacers being similar on each side of their horizontal median line.

4. The structure of claim 3 with the cover sheets of plywood.

5. A grain door section comprising two rectangular cover sheets of greater length than width having the end portions of their adjacent narrow ends glued to each other to form a flat bearing surface on both sides of both ends of the door section that portion of each sheet between said glued together end portions being arched oppositely to the other sheet and a plurality of like longitudinal spacers positioned between and glued to the cover sheets said spacers being similar on each side of their horizontal median line with their middle portions parallel.

6. A grain door section comprising two rectangular cover sheets of greater length than width having the end portions oftheir adjacent narrow ends glued to each other to form a fiat bearing surface on both sides of both ends of the door section that portion of each sheet between said glued together end portions being arched oppositely to the other sheet and a plurality of like longitudinal spacers positioned between and glued to the cover sheets said spacers being similar on each side oftheir horizontal median line with the middle third portion of their-length parallel.

References Cited in the file of this patent UNITED STATES PATENTS 1,428,714 Schwamb Sept. 12, 1922 2,388,485 Jensen Nov. 6, 1945 2,479,819 De Ragon Aug. 23, 1949 FOREIGN PATENTS 752,843 France Sept. 30, 1933 590,396 Great Britain July 16, 1947 

